2009 Audi S4 Tire Size

The original tire size for your 2009 Audi S4 is listed below. Tap on the box to view a color-coded explanation of the best Audi S4 tire size.

Trim Options:

Cabriolet

235/40ZR18/RF 95Y

Simplified Size:  235-40-18

Simplified size is useful for shopping and buying tires.

The original tire size for your 2009 Audi S4 is 235/40ZR18/RF 95Y.  A color-coded explanation of the 2009 Audi S4's tire size is shown below.

235

This number indicates that your tire has a width of 235 millimeters.

18

The tire size was designed to fit rims or wheels that are 18 inches in diameter.

RF

The mark of RF indicates that the tire is reinforced.  This means it can handle a higher inflation pressure than a standard tire, which increases its maximum load.

95

This tire has a load index of 95, which means it's capable of carrying a load of 1518 pounds (690 kg) or less.  A higher number means the tire can carry more weight.  A lower number means the opposite.

Z

This tire has a speed class of Z, which means it's part of an elite speed class of 149 mph or more (240 km/h).  A tire's speed class is less specific than the speed rating.

40

This number means that your tire has an aspect ratio of 40%.  In other words, your tire's sidewall height (from the edge of the rim to the tire's tread) is 40% of the width.  In this case, the sidewall height works out to be 94 millimeters.

R

This letter denotes how your tire was constructed.  Radial is the standard construction method for about 99% of all tires sold today.

RRadial
BBias Belt
DDiagonal
Y

This tire has a speed rating of Y, which means 186 mph (300 km/h) is the maximum speed that can be sustained for 10 minutes.  A higher speed becomes dangerous.